It's unclear what the purpose of the additional storage is, but it's likely tied to future firmware updates, hinting that Apple could have more plans for the Studio Display's built-in A13 chip.
Apple's A13 Bionic Chip is also featured in its 2019 iPhone 11 series, 2nd-gen iPhone SE and 9th-gen iPad. All three devices only feature a storage configuration as low as 64GB, so there's a possibility the Studio Displays 64GB of internal storage could be tied to the chip's architecture.
Apple's Studio Display has received a lukewarm reception from most critics. While the display itself features the sleek, brushed metal design the tech giant is known for, early reports indicate issues with its built-in 12-megapixel ultra-wide camera. Apple says it plans to fix this issue through an upcoming Studio Display software update.
I found the 5K Studio Display to be a decent monitor, though I’m disappointed it doesn’t support a 120Hz refresh rate at lower resolutions.
For more on Apple’s Studio Display and Mac Studio, check out my in-depth story about both devices.